1. Field of the Invention
The present invention is related, in general, to a gas turbine engine system, and more particularly, to a technology for controlling fuel combustion in a gas turbine engine with an annular combustion system.
2. Description of the Related Art
Gas turbines are widely used to supply power for various machines, such as ships, vehicles, airplanes, and electric generators. As shown in FIG. 1, an exemplary gas turbine includes a compressor(not shown), an annular combustor 101, a turbine 102, and a fuel supply system 103. The combustor 101 is provided with compressed air from the compressor and fuel from the fuel supply system 103. The fuel supply system 103 includes a main fuel flow regulator 103a which controls the flow of the fuel supplied for the combustor 101. The fuel is mixed with the compressed air, and burned in the combustor 101. The resulting flow of combustion products out of the combustor 101 drives the turbine 102.
The combustor 101 includes an annular outer casing 104 and an annular liner 105, which are disposed coaxially about the longitudinal centerline axis of the combustor 101. The compressed air from the compressor is introduced between the outer casing 104 and the liner 105. A plurality of fuel nozzles 106 (one shown) are disposed in the liner 105, being spaced at substantially equal intervals in the circumferential direction. The liner 105 has a combustion air hole (not shown) to introduce combustion air into the liner 105.
The fuel provided for the combustor 101 is delivered to each fuel nozzle 106. The fuel nozzles 106 inject the fuel into combustion zone 105a in the liner 105. The injected fuel is burned to produce combustion gas.
The liner 105 has dilution holes 107 to introduce dilution air 107a immediately downstream of the combustion zone 105a. The combustion gas is delivered to the turbine 102 after being mixed with the dilution air 107a. The turbine 102 is driven by the combustion gas.
Optimization of the state of the combustion in the combustor is of much importance. A gas turbine engine for optimizing the state of the combustion zone is disclosed in Japanese Open Laid Patent Application No. Jp-A 2000-46332, and Japanese Open Laid Patent Application No. Jp-A Heisei 5-195822. The disclosed gas turbine engine includes fuel nozzles (or burners) in a combustor, the fuel nozzles being grouped into two or more individually controllable nozzle groups. The individual control of the nozzle groups achieves optimized combustion state in response to the operational states of the gas turbine engine.
In a gas turbine with an annular combustor, various factors may undesirably cause inhomogeneous flame temperature and turbine inlet temperature in the circumferential direction of the combustor. The factors may include inevitable differences in dimensions of a liner and fuel nozzles, inhomogeneous distortion of the liner, and unstable combustion.
Inhomogeneous flame temperature may result in emissions of environmental pollutants, including carbon monoxide (CO), oxides of nitrogen (NOx), and unburned hydrocarbon (UHC). Inhomogeneous flame temperature may result in a flame temperature which is excessively increased in one potion of the combustion zone while being inappropriately decreased in other portion. Excessively high flame temperature causes emission of oxides of nitrogen, which are generally referred to as NOx, and inappropriately low flame temperature causes emission of carbon monoxide. In addition, the inhomogeneous flame temperature may cause a blowout in the combustor.
Furthermore, a non-homogeneous turbine inlet temperature may result in a turbine inlet temperature which is excessively increased in one potion of the turbine. Excessively high turbine inlet temperature may damage the blades of the turbine.